Thermotropic liquid crystalline polymers are classified as “rigid rod” polymers as their molecular structure is typically composed of aromatic units linked by functional groups such as esters and/or amides. The rigid, rod-like structure allows the polymers to exhibit liquid crystalline behavior in their molten state (thermotropic nematic state). Due to the presence of this nematic state in the melt, these materials also exhibit unique rheological properties. One such property is a “shear thinning behavior” characterized by a decrease in complex viscosity with increasing shear rates. This high shear thinning behavior is particularly attractive in the fabrication of parts with intricate geometries (e.g., electrical connectors) because the polymers can flow well under heat and shear to uniformly fill complex parts at fast rates without excessive flashing or other detrimental processing issues. Despite these benefits, conventional liquid crystalline polymers sometimes exhibit a reduced “low shear” shear viscosity that can lead to “drooling” during processing, thereby leading to problems in uniformly filling the part. Furthermore, such polymers may also have a lower melt strength during melt processing, making it difficult for the resulting material to maintain its physical integrity. The lack of adequate melt strength and physical integrity becomes particularly problematic in non-molding applications, such as when the polymer is thermoformed into a sheet or film. Attempts have been made to increase the “low shear” viscosity by increasing the molecular weight of the polymer. However, this also increases the “high shear” viscosity, which can compromise the flow of the material.
As such, a need exists for a liquid crystalline polymer composition that exhibits excellent rheological properties under both low and high shear conditions, as well as a method of forming such polymers.